[Extensions] Don't allow built-in extensions code to be overridden

extensions/renderer/api_test_base.cc

Index: extensions/renderer/api_test_base.cc
diff --git a/extensions/renderer/api_test_base.cc b/extensions/renderer/api_test_base.cc
index 53d6fa4923870a17efc05f602f84e20bca28d6ad..03158926eb457c05f35dc9c5c9e1f4ce21425722 100644
--- a/extensions/renderer/api_test_base.cc
+++ b/extensions/renderer/api_test_base.cc
@@ -140,17 +140,18 @@ void ApiTestEnvironment::RegisterModules() {
                           "unit_test_environment_specific_bindings.js");
 
   env()->OverrideNativeHandler("activityLogger",
-                               "exports.LogAPICall = function() {};");
+                               "exports.$set('LogAPICall', function() {});");
   env()->OverrideNativeHandler(
       "apiDefinitions",
-      "exports.GetExtensionAPIDefinitionsForTest = function() { return [] };");
+      "exports.$set('GetExtensionAPIDefinitionsForTest',"
+                    "function() { return [] });");
   env()->OverrideNativeHandler(
       "event_natives",
-      "exports.AttachEvent = function() {};"
-      "exports.DetachEvent = function() {};"
-      "exports.AttachFilteredEvent = function() {};"
-      "exports.AttachFilteredEvent = function() {};"
-      "exports.MatchAgainstEventFilter = function() { return [] };");
+      "exports.$set('AttachEvent', function() {});"
+      "exports.$set('DetachEvent', function() {});"
+      "exports.$set('AttachFilteredEvent', function() {});"
+      "exports.$set('AttachFilteredEvent', function() {});"
+      "exports.$set('MatchAgainstEventFilter', function() { return [] });");
 
   gin::ModuleRegistry::From(env()->context()->v8_context())
       ->AddBuiltinModule(env()->isolate(),